1. Field of the Invention
This invention relates to a connector having a number of contacts arrayed at narrow pitches on a base member, and particularly to an array structure of a group of contacts on the base member.
2. Brief Description of the Prior Art
The conventional mount-to-contact type IC socket as represented by Japanese Utility Model Publication No. Hei 2-31790 has a structure in which each contact has a horizontal U-shaped contact element, an upper U-curved element of the horizontal U-shaped contact element is formed as a contact element on which a terminal of an IC is to be mounted for contact, and a lower U-curved element thereof is formed as a seat element received on an upper surface of a base member. For each of the contact elements, a male terminal extending downward from the seat element is preliminarily pressingly fitted in an implanting hole formed in the base member, and a press-fit claw disposed at a basal portion of the male terminal is caused to bite into an inner wall of the implanting hole thereby providing an array structure of a plurality of contacts arranged at narrow pitches on the base member.
In recent years, as the manufacturing technique progresses, IC's are increased in pole number and miniaturized. Therefore, IC's of narrow pitches, in which IC terminals are arranged at 0.2 mm pitches or at similar pitches, are commercially available. Therefore, sockets which are suitable for such IC's are demanded. Especially, a group of contacts arrayed on a socket are required to be implanted at narrow pitches so as to correspond to the narrow pitches of the IC terminals. This naturally follows that the pitches of the implanting holes of the contacts are required to be reduced, and the sizes of the contacts are required to be more and more miniaturized.
However, the conventional structure, in which contact implanting holes are preliminarily formed in a base member and male terminals of contacts are press fitted therein, has the following problems. By reason of the reduced pitches of the contact implanting holes, the thickness of a wall between adjacent contact implanting holes becomes extremely thin, and is therefore difficult to shape. Even if shaping is possible, a wall having a thickness sufficient to bear the press-fit of a press-fit claw is unobtainable. On the contrary, the male terminals become thinner and thinner as the miniaturization of contacts progresses and a sufficient amount of projection of the press-fit claw is difficult to obtain. As a result, it is difficult to provide a claw which is sufficiently strong to bear the press-fit.